Process of fixing mechanical finishes to cellulose fabrics by applying isocyanate-bisulphite addition salts



United States Patent PROCESS or FIXING MECHANICAL FINISHES T0 cE Lu osE FABarcs BY APr -YING ISOCYA- NATE-BIsULPmrE AnnrrroN SALTS John Gwynant Evans, Menston-in-Wharfedale, James Harr Leach, Morley, Leeds, and William Salkeld Meals, Bradford, England, assignoi's to The Bradford Dyers Association Limited, Bradford, England, a company of Great Britain No Drawing. Application March 2, 1951, Serial No. 213,691

Elms-priority, application Great Britain -March 10, 1950 2 Claims. (Cl. 8-1161) This invention relates to the treatment of cellulosic materials whereby they are given an enhanced resistance to water or steam of efiects produced mechanically on such materials. By cellulosic materials we mean cellulo'si'c films, foils, paper and pulp, yarns, fibres and woven or non-woven, e. g. knitted, felted or bonded-Web, fabrics of natural or regenerated cellulose, cellulose esters or ethers or their mixtures with other fibres. In the case of certain finishing effects, e. g. embossing and moire, the invention is also applicable to fabrics composed wholly or mainly of natural silk, and such fabrics are included by the term cellulosic materials.

The mechanical finishes which come into consideration include, for example, pressing, calendering, schreinering, embossing, beetling, rippling, the special finishes known as moire and cire, and mechanically enforced dimensional adjustment such as hereinafter described. Other 'finishes include the crimping and polishing of yarns, and the finish obtained 'by folding a fabric and pressing so as to form pleats. Normally these finishes are very sensitive 'to moisture and they may be substantially diminished or even destroyed by water or by steam pressing processes such as are common in the final stages of garment manufacture or by laundering. It is the object at the present invention to provide a process which will substantially overcome such disadvantage. ln a cospending application Serial No. 200,312, fiied December Ill, 1950, now'abandoned, we have described the use of aliphatic and aromatic isocyanates and isothiocyana't-es applied from aqueous emulsion td-textiles, followed by drying and mechanical treatment with or with out a subsequent heat treatment as a means of producing mechanical finishes of much improved resistance to launderingand to the influence of moisture generally.

We have now discovered that the reaction products of bistilphites with monoor'poly-fu'nctional isocyana'tes and isothiocyanates (hereinafter termed isocyanate-bisul- ,pliite reaction products) may be very advantageously used in a similarmanne'r "to produce moistureand "wash-- resistant mechanical finishes on cellulosic materials. Except in the specific examples, the term isocyanat'e will be used hereafter to include isothiocyanate. The term chalcogen having an atomic weight not exceeding that of sulphur, covers oxygen and sulphur only in accordance withaccepte'd terminology.

This discovery is all the more unexpected since we have evidence that the nature of the reaction when the isocyanate bisulphite reaction products "are applied to cellulosic materials and heated is differentfrom the reaction of the corresponding isocyanates themselves. This evidence is disclosed in our co-pending application Serial No. 213,692, filed March 2, 1951, relating to the modification of properties of cellulosic materials by th'eapplication of these is'ocyanate-bisulphite reaction products. Therein it is described, inter alia, that, whereas the application of an isocyanate to a cellulosic material followed by -heating, results in a decreased afiinity for direct dyes, the application of the corresponding isocyanatebisulphite reaction product under similar conditions has a diametrically opposite effect and increases the affinity for direct dyes.

The process according to the present invention comprises incorporating in a cellulosic material an isocyanatebisulphite reaction product, applying the effect or finish thereto and submitting it to heat. The preferred method is to impregnate the materials with an aqueous solution or dispersion of the 'isocyanate-bisulphite reaction product, dry or partially dry the material, then apply the effect or finish and submit the material to heat. It will be understood that, when applying the said reaction prodnot -in an aqueous medium, the mechanical finish must be applied afterwards, since it would otherwise be impaired by the aqueous medium.

The optimum temperature for the heat treatment is the decomposition temperature of the isocyanate-bisulphite reaction product used. The heat treatment will normally be of 3-15 minutes duration at a temperature of C. to 200 C., but :if a lower temperature is used the time necessary will be substantially greater. It may be possible, in some cases, to carry out the mechanical finishing treatment and the heat treatment simultaneously. The heat treatment may be carried out by any of the conventional methods, but preferably is effected between C. and 189 C. for a few minutes in stenters or hot air chambers or through machines which use infra-red radiation as the source of heat. Alternatively this heat treatment may be effected by passing the material through a bath of molten metal, e. g. containing low temperature melting alloys, or less preferably may be effected by treating the material with steam.

One method of making the isocyahate-bisulphite reaction products is to-di'sperse the isocyanate in a saturated aqueous solution of an alkali metal bisulphite, e. g. sodium bisulphite, preferably in about equimolecular proportions, from which-after a short time the isocyanatebisulphite reaction product will separate out. Liquid isocyanates may be stirred into the saturated bisulphite solution but solid isocyanates should 'be dissolved in an organic solvent such as benzene, toluene or Xylene first.

The isocyanate-bisulphite reaction products may be dried at relatively low temperatures to white odourless solids. They are in many cases soluble in water to give stable solutions in cont-radistinction to the corresponding isocyana'tes whicharedecomposed by water. The sodium compounds of=isocyanate-bisulphite reaction products are generally soluble in Water, but the corresponding potassium salts are not so readily soluble in water. Where the solubility of the salts is low they can be used in aqueous dispersion. Conditions of use which :lead to the hydrolysis of-the reactionproducts, e. g. heating of aqueous solution, should be-avoided.

Alternatively to, but less rpreferably than, the application or the isooyanate-bisulphite reaction :product itself to the material; this product can be produced in situ either by 'the application of the isocyanate first followed by the bisulphite, or vice-versa, in both cases with a final heat 'treatmentas already described. Thus the isocyanate may be applied to the material from a solution in an organic solvent which is then evaporated whereafter the bisulphite is applied from aqueous solution, and the cellulosic material driedahd heat treated. Similarly the bisulphife can be applied to the material first from an aqueous solution followed by drying and the application of the isocyanate from an organic solvent solution, the solvent is evaporated and the heat treatment carried out.

A further modification of the invention includes the emulsification of the isocyanate in a dilute aqueou bisulphite solution and the application of this emulsion to the cellulosic material, followed by drying and heating. In dilute solutions of bisulphites the reaction does not readily take place but on drying and concentrating on the fabric the isocyanate-bisu'lphite reaction can be carried out.

Although mono-functional isocyanates may be used to react With the bisulphite, it is preferable to use poly-functional isocyanates such as a dior tri-isocyanate. In the case of the aromatic isocyanates, the tri-functional are preferred to the di-functional, whilst, in the case of the aliphatic isocyanates, it is preferred to use the di-functional having an aliphatic chain of not more than carbon atoms. If monofunctional isocyanates are to be used, it is preferable that they be either aromatic isocyanates or aliphatic isocyanates with a chain containing not more than 8 carbon atoms. The isocyanates and isothiocyanates which are employed in accordance with the present invention are monomeric compounds of the formula R.(NZCX)n where X is a chalcogen having an atomic weight not exceeding that of sulphur, n is a whole number not exceeding 3, and R represents monomeric aromatic and aliphatic hydrocarbon radicals, the aromatic radicals having monocyclic aryl hydrocarbon groups of not more than seven carbon atoms and the aliphatic hydrocarbon radicals having a chain of not exceeding ten carbon atoms and when n is 1, contain not more than eight carbon atoms. The bisulphite reaction products are addition salts having the formula R.(NH.CX.SO3M)n where X, n and R are as defined above, and M is an alkali metal.

Specific examples of suitable isocyanate-bisulphite reaction products are the bisulphite reaction products of phenyl isocyanate, hexamethylene di-isocyanate, m-toluylene di-isocyanate, m-phenylene diisocyan-ate, the mixture of poly-isocyanates in xylene solution under the registered trademark Vulcafor V. C. C., and any of the corresponding isothiocyanates, and also allyl isothiocyanate. Fuither examples include the bisulphite reaction products of toluene 2:4 di-isocyanate, toluene 2:4:6 tri-isocyanate, mixtures of toluene 2:4 and 2:6 di-isocyanates and methylene bis-p-phenylene isocyanates.

We have found that the heat treatment may also be advantageously elfected in the presence of an amide, an amidine or an amino-triazine. These are preferably added to the aqueous solution of the isocyanate-bisulphite reaction product and the process carried out as already described.

Suitable amides are urea, thiourea, acetamide, sulphonamide or p-toluene sulphonamide and dicyandiamide; suitable amidines include guanidine and amino guanidine, and suitable amino triazines include melamine.

The improvement which is brought about by these amides, 'amidines or amino triazines is demonstrated by the firmer handle of the finished fabric and the greater resistance of the finished effect to Washing.

It will be clear that by local application of the bisulphite compounds as by printing or stencilling it is possible to get patterned effects on washing in which the mechanical finish has been fixed locally. Alternatively, the isocyanate-bisulphite reaction product may be applied all over the fabric but be rendered locally ineffective by the prior local application to the fabric of chemical resists, e. g. strongly alkaline pastes, or be prevented from reaching certain portions of the fabric by the prior application of mechanical resists, e. g. waxes to such portions. As a further alternative, discharge methods may be used, e. g. by applying the isocyanate-bisulphite reaction product all over the fabric and then, prior to the heat treatnaent, applying a pattern of a strongly alkaline paste.

The present invention may often be used with advantage in conjunction with the above-mentioned dye process described in our co-pending application Serial No. 213,692. For example, a dye may be included in the solution of the isocyanate-bisulphite reaction product before applying same to the material to be treated, thereafter effecting the mechanical finishing treatment. Alternatively dye may be applied after the mechanical finishing treatment and after the subsequent heat treatment.

Apart from water solubility and the stability of their aqueous solutions a great advantage of the isocyanatebisulphite reaction products as compared with the cor-' responding isocyanates is the pleasanter and more efficient operating conditions. Many of the isocyanates are volatile during drying and heating and their fumes have, in a number of cases, pronounced physiological effects. The isocyanate-bisulphite reaction products give rise to no fumes, thus avoiding unpleasant effects on the operatives and, since the whole of the agent applied to the textile is used and not lost as vapour, the process is more elncient.

It has been found that the present invention may very suitably be used in the case Where the mechanical finish is designed to alter forcibly the dimensions of a fabric.

For example, a well known method for producing a dimensionally-adjusted woven fabric is to pass the fabric through a machine which forcibly reduces the dimensions of the fabric by pressing the yarns closer together, or, if so desired, which forcibly increases the dimensions of the fabric by pulling the yarns further apart. Such machines are described in British specifications No. 359,759 and No. 372,803.

The invention is applicable to fabrics that have already been finished in a conventional manner, that is to say the treatment may be applied for example to fabrics which contain softening agents, lubricating agents, antiseptics or which have been anticreased or stabilised by means of thermosetting resinous condensates.

The invention may also be applied by treating fabrics with the isocyanate-bisulphite reaction products before or simultaneously with conventional finishing agents.

In the following examples which illustrate the invention the parts are by weight.

Example I 84 parts of hexamethylene di-isocyanate are added to 310 parts of a solution of sodium bisulphite in water containing 104 parts of sodium bisulphite. The two liquids are intimately mixed by means of vigorous agitation, and as the reaction proceeds a white crystalline solid separates. The mix eventually becomes a stiff paste, from which the bisulphite compound can be obtained by filtration and washing with acetone, followed by drying at 5060 C.

A plain cotton fabric is impregnated in a solution prepared by dissolving 7.5 parts of the compound prepared as above in 92.5 parts of water. The fabric after mangling is partially dried so that it retains 15% of mois ture, and glazed by passage between a heated metal cylinder at 200 C., and a compressed paper bowl. The glazed fabric is now heated to 150 C. for 10 mins.

The glaze imparted to the fabric is now resistant to repeated washing in aqueous soap solutions at C Example ll A mercerised cotton fabric is impregnated in a solution containing 10 parts of hexamethylene di-isocyanate bisulphite compound prepared as in Example I, in parts of water, mangled and dried at open width on a stenter. The dry fabric is steam moistened, and cire embossed by passage between a heated engraved metal cylinder at 180 C., and a compressed paper bowl. The embossed fabric is then heated to C. for 10 minutes. The embossed pattern is now resistant to repeated washing in soap.

Example *lll A plain patron fabric is priri'tedftliiough 'a sak-sateen with a thickened paste made as follows. I parts" of the bisulphite tamarin or hiram'ethylene ii-isocyanate, preps'ra as in Example I, is dissented in 45 pai't's or water and this soliition is stirred into a dispersion of 4 parts or locust bean gum in 46 parts of d, M V The printed fabric is dried, and steamed so that it contains 15% moisture, and g la'zed by passage between a heated metal cylinder at 180 Q, and a compressed paper bowl. The fabric is then 'vvasli ed in aqueous s'oa'p solution at so "0., w en are glaze in the impniitea parts is removed, whereas that in the printed parts" is retained. In this way a idealized glazed enact is produced which is resistant to laundering.

Example IV A cotton fabric is impregnated in a solution containing 4 parts of dicyar'idianiide aaas ans ofjthe bisulphite compound of hexain'ethylene di-isocyana'te, prepared as in Example I, in 90 parts of water. After impregnation the fabric is partially dried until it contains 15% of moisture, and is 'then glazed in known manner on a calender at 200 C. I Theglazed fabric is then subjected to a heat treatment at 150 C. for minutes. The incorporation of dicyandiamide results in a much firmer handle of -the glazed fabric, the characteristics of which are resistant to repeated laundering.

Example I A plain cotton fabric is printed as in Example III. The steamed, dried fabric is glazed in known manner on a calender at 190 C., and heated at 150 C. for 10 minutes. The g'la'zedfabric is "then passed into a dyebath at 90 C. containing 0.5 gm. per litre Polar Brilliant Red G (GeigyColour Company)( New Colour Index Acid Red No. 122) and 5.0 gms. per litre sodium sulphate, with a volume ratio of 40:1. In this way, the fabric is dyed in the printed parts which at the same time retain their lustre, the unprinted parts lose their lustre in the hot dyebath, and are not dyed. In this way a coloured localized glazed fabric is produced fast to Washing.

Example VI A plain cotton fabric is printed through a silk screen with a thickened paste made in the following manner:

5 parts of the bisulphite compound of hexamethylene di-isocyanate prepared as in Example I are dissolved in 20 parts of water and stirred into 30 parts of a dispersion containing 3 parts of locust bean gum. 2 parts of Polar Brilliant Red G are dissolved in 40 parts of water and this solution is stirred into the paste.

The printed fabric is dried, and steam moistened, glazed on a calender at 190 C. in known manner, followed by heating at 150 C. for 10 minutes. The glazed fabric is then secured in dilute aqueous soap solution at 40 C. for 10 minutes when the glaze in the unprinted parts is removed. Thus a coloured printed glazed effect is produced which will withstand soaping at 70 C.

Example V11 A plain cotton fabric is impregnated in a solution containing 10 parts of hexamethylene di-isocyanate in 90 parts of benzene, and dried to remove the solvent at 60 C. The fabric is then padded through a solution containing 15 parts of sodium bisulphite in 85 parts of water. After mangling the fabric is maintained in the wet condition for 2 hours during which time the reaction between the isocyanate and the sodium bisulphite proceeds.

The fabric is then partially dried, so that it retains 15% of moisture, and embossed by passage between a heated engraved metal cylinder at 150 C., and a superelastic cotton bowl. The embossed fabric is then heated to 150 C., for 10 minutesrfo llowedby rinsing in water at 45 C.. The embossed design on the fabric is resistant to washing at 70 C. in dilute aqueous soap solutions.

Example VIII The potassium bisulphite reaction product bf herd methylene iii-isocyanate is prepared by first reacting hexaiii'thylene diisocyanateand sodium bisulphite solution as described in Example I. The paste 'so obtained is dissolved in 310 parts of water and the "solution is heatdft'o 60 C with the additio'nof 84 parts "of potassiuin chloride and filtered to remove impurities. 'Oii cbo'lin'g to 5 C. crystals of "the more sparingly s'oluble potassium salt are obtained. 7 y p t A plain co't'toh fabric is impregnated ina solution coir t'ai'nirig l'Ojparts of the potassium bisulphite compound of hexamethylene' di-isocyanate and 5 parts of urea in 85 pans of'wate'n The fabric is dried 'so that it contains approximately 15% -of moisture and iS then embossed by passage between an engraved metal cylinder at 180 ai'id compressed paper bowl. The fabric 'is heated at 1'45 C. for 10 minutes. The embossed 'design i's mow resistant to repeated washing in 'soap -s'olutioil.

Example IX 30 :parts 'of 'metatoluylene di-isocyanate 'aremixed with '130 gins. "of sodium bisulphite solution, gms. of which contain 30 *grns. of sodium bisulphite. The two liquids are intimately mixed by means of vigorous agitation, and after 2 hour'sthe mix becomes a stiff .paste. The solid precipitate is filtered, washed and dried at '60 C.

A cotton fabric incorporating a woven design 'is impregnated in a solutionof 5'parts of the bisulphite reaction product with meta toluylene iii-isocyanate in '95 parts of water and dried. The dry fabric is steam moistened, and friction glazed bypassing between a heated metal cylinder at 180 C., and a compressed paper bowl. Theglazed fabric is then heated at C. for 10 minutes. The glazed effect is now resistant to repeated washing in soap :solutio and the woven design is considerably enhanced in appearance.

Example X A warp twill viscose rayon staple-fibre fabric is impregnated in a solution containing 10 parts of hexamethylene di-isocyanate bisulphite compound, prepared as in Example I, in 90 parts of water, mangled and dried. The fabric is then compressively shrunk by treatment as described in British Patent No. 372,803 and heated at C. for 10 minutes. The effect of this treatment is illustrated in the following table showing the amount of shrinkage obtained by washing the fabric in a liquor containing 0.25 part of soap per 100 parts of aqueous solution.

Warp Weft shrinkage, shrinkage, percent percent 1. Untreated fabric 14. 0 2. 5 2. As 1, compressivley shrunk according to B. P. 372,503 6. 4 1.0 3. Fabric impregnated in sodium bisulphite compound of hexamethylene di-isocyanate, compresslvely shrunk according to B. P. 372,503 and heated 2. 1 0. 6

Example XII A- viscose rayon staple-fibre yarn is impregnated with a solution of parts of the sodium bisulphite reaction product of hexamethylene di-isocyanate and 5 parts of urea in 85 parts of water. The yarn is partially dried to a moisture content of deformed by crimping, and then heated at 145 C. for 10 minutes. The crimp is rendered durable to repeated soaping.

What we claim is:

1. Process for improving the resistance to water and aqueous treatments of efiects produced by mechanical treatment on cellulose textiles comprising impregnating such material with a bisulphite addition salt having the formula R.(NH.CX.SO3M)n where X is a chalcogen having an atomic Weight not exceeding that of sulphur, n is a whole number not exceeding 3, M is an alkali metal, and R represents monomeric aromatic and aliphatic hydrocarbon radicals, the aromatic radicals having monocyclic groups of not more than seven carbon atoms and the aliphatic hydrocarbon radicals having a chain not exceeding ten carbon atoms, and when n is 1 not more than eight carbon atoms, applying the mechanical treatment to produce the desired effect, and submitting the material to heat at a temperature at least as high as the decomposition temperature of the addition product but below that of any deleterious effect on the impregnated material, in which process there is also applied to the material a compound selected from the group consisting of urea, thiourea, dicyandiamide, p-toluene sulphonamide, guanidine, amino-guanidine and melamine, so that said compound is present in the material during the heat treatment.

2. Process for improving the resistance to water and aqueous treatments of effects produced by mechanical treatment on cellulose textiles comprising impregnating such material with a bisulphite addition salt having the formula R.(NH.CX.SO3M)n where X is a chalcogen having an atomic weight not exceeding that of sulphur, n is a whole number not exceeding 3, M is an alkali metal, and R represents monomeric aromatic and aliphatic hydrocarbon radicals, the aromatic radicals having monocyclic groups of not more than seven carbon atoms and the aliphatic hydrocarbon radicals having a chain not exceeding ten carbon atoms, and when n is 1 not more than eight carbon atoms, applying the mechanical treatment to produce the desired effect, and submitting the material to heat at a temperature at least as high as the decomposition temperature of the addition product but below that of any deleterious effect on the impregnated material, in which process the impregnation is with an aqueous medium containing the addition salt and the impregnated material is at least partially dried prior to application of the mechanical treatment, and in which the aqueous medium includes a compound selected from the group consisting of urea, thiourea, *dicyandiamide, p-toluene sulphonamide, guanidine, amino-guanidine and melamine, so that said com pound is present in the material during the heat treatment.

References Cited in the file of this patent UNITED STATES PATENTS 2,121,005 Bener June 21, 1938 2,121,006 Bener June 21, 1938 2,123,153 Rivat July 5, 1938 2,217,696 Milbu'rn Oct. 15, 1940 2,284,895 Hanford June 2, 1942 2,339,913 Hanford Jan. 25, 1944 2,370,405 Kaase Feb. 27, 1945 2,468,716 Nyquist et a1 Apr. 26, 1949 2,643,958 Kleiner et al June 30, 1953 2,710,816 Evans et al. June 14, 1955 FOREIGN PATENTS 521,116 Great Britain May 13, 1940 OTHER REFERENCES Chemical Abstracts, vol. 44, January 1950, pages 116. 

1. PROCESS FOR IMPROVING THE RESISTANCE TO WATER AND AQUEOUS TREATMENTS OF EFFECTS PRODUCED BY MECHANICAL TREATMENT ON CELLULOSE TEXTILES COMPRISING IMPREGNATING SUCH MATERIAL WITH A BISULPHITE ADDITION SALT HAVING THE FORMULA R.(NH.CX.SO3M)N WHERE X IS A CHALCOGEN HAVING AN ATOMIC WEIGHT NOT EXCEEDING THAT OF SULPHUR, N IS A WHOLE NUMBER NOT EXCEEDING 3, M IS AN ALKALI METAL, AND R REPRESENTS MONOMERIC AROMATIC AND ALIPHATIC HYDROCARBON RADICALS, THE AROMATIC RADICALS HAVING MONOCYCLIC GROUPS OF NOT MORE THAN SEVEN CARBON ATOMS AND THE ALIPHATIC HYDROCARBON RADICALS HAVING A CHAIN NOT EXCEEDING TEN CARBON ATOMS, AND WHEN N IS 1 NOT MORE THAN EIGHT CARBON ATOMS, APPLYING THE MECHANICAL TREATMENT TO PRODUCE THE DESIRED EFFECT, AND SUBMITTING THE MATERIAL TO HEAT AT A TEMPERATURE AT LEAST AS HIGH AS THE DECOMPOSITION TEMPERATURE OF THE ADDITION PRODUCT BUT BELOW THAT OF ANY DELETERIOUS EFFECT ON THE IMPREGNATED MATERIAL, IN WHICH PROCESS THERE IS ALSO APPLIED TO THE MATERIAL A COMPOUND SELECTED FROM THE GROUP CONSISTING OF UREA, THIOUREA, DICYANDIAMIDE, P-TOLUENE SULPHONAMIDE, GUANIDINE AMINO-GUANIDINE AND MELAMINE, SO THAT SAID COMPOUND IS PRESENT IN THE MATERIAL DURING THE HEAT TREATMENT. 